The use of wireless communication devices such as telephones, pagers, personal digital assistants, laptop computers, etc., hereinafter referred to collectively as “mobile appliances” or “mobiles stations” has become prevalent in today's society. In recent years, at the urging of public safety groups, there has been increased interest in technology which can determine the geographic position or “geo-locate” a mobile station in certain circumstances.
Determining the location of a mobile station may require one or more types of calibration data associated with the mobile station (e.g., signal strength, round trip time, time difference of arrival (TDOA), etc.). Calibration data is typically collected in an outdoor environment. The primary reason for collecting calibration data outdoors is the greater ease of collecting data via automated calibration collection procedures or via manual collection procedures along roads. It is time-consuming to perform calibration procedures at geographical locations that are likely to include mobile stations but are not accessible by roads, such as, indoor locations, pathways, parks, etc.
Intentionally avoiding calibration data collection procedures in areas that are not accessible by motorized vehicles would simplify the calibration data collection procedure. If, however, there is any probability that a mobile station is likely to be located in these non-calibrated areas, then failing to obtain certain calibration data may be detrimental to locating the mobile station.
Obtaining calibration data in areas that are not accessible by vehicles and/or other types of automated data collection devices without performing manual calibration procedures would increase productivity and reduce associated costs.
One embodiment of the present subject matter is a method to determine calibration data at a candidate location by determining the candidate location in the non-calibrated sub-region to measure calibration data and obtaining calibration data for a previously calibrated geographical region within communication range of the candidate location. The method may further determine a function to represent at least a portion of the calibration data of the calibrated geographical region, and estimate the calibration data at the candidate location based on the function.
Another embodiment of the present subject matter is a method to determine calibration data at a candidate location by determining the candidate location in the non-calibrated sub-region to measure calibration data and determining a varying power function of signal power received from at least one neighboring base station to represent calibration data of at least a portion of a calibrated geographical region adjacent to the non-calibrated region. The method may further estimate the calibration data at the candidate location based on the function.
Another embodiment of the present subject matter is a method to determine calibration data at a candidate location by determining the candidate location in the non-calibrated sub-region to measure calibration data and determining a varying power function of signal powers received from a plurality of neighboring base stations to represent calibration data of at least a portion of a calibrated geographical region adjacent to the non-calibrated sub-region. The method may further determine at least one lowest signal power level of the plurality of signal power levels received, omit the signal power of the base station that transmitted the lowest signal power level from the varying power function, and estimate the calibration data at the candidate location based on the function.
Yet another embodiment of the present subject matter is a method to determine calibration data at a candidate location by determining the candidate location in the non-calibrated sub-region to measure calibration data and providing calibration data for a calibrated geographical region within communication range of the candidate location. The method may also determine a first function to represent at least a first portion of the calibration data of the calibrated geographical region, determine a second function to represent at least a second portion of the calibration data of the calibrated geographical region, where the second portion may be different from the first portion, and estimate the calibration data at the candidate location based on the first and second functions.
Still yet another embodiment of the present subject matter is a method to implement a system to determine calibration data in a non-calibrated sub-region including a calibration data collection device to collect and store calibration data within a first portion of a geographical region. A computing device may then locate a candidate location within a non-calibrated portion of the region, select a previously calibrated geographical region within communication range of the candidate location, determine a function to represent at least a portion of the calibration data of the calibrated geographical region, and estimate the calibration data at the candidate location based on the function.
These and other advantages of the disclosed subject matter over the prior art will be readily apparent to one skilled in the art to which the disclosure pertains from a perusal of the claims, the appended drawings, and the following detailed description of the preferred embodiments.